1. Field of the Invention
Embodiments of the present invention relate to systems designed for utilizing of heat source streams having an initial temperature between about 200° F. and about 500° F., such as geothermal heat sources and other heat sources with a similar temperature range.
More particularly, embodiments of the present invention relate to systems designed for utilizing of heat sources streams having an initial temperatures between about 200° F. and about 500° F., such as geothermal heat sources and other heat sources with similar a temperature range, where the system includes a two staged condensation subsystem. The system is specifically designed for use in applications, where the temperatures of cooling water or air are relatively high, e.g., 80° F. or higher. This makes the system well suited for use in geothermal applications in tropical and subtropical climates.
2. Description of the Related Art
In U.S. Pat. No. 4,982,568, a working fluid is a mixture of at least two components with different boiling temperatures. The high pressure at which this working fluid vaporizes and the pressure of the spent working fluid (after expansion in a turbine) at which the working fluid condenses are chosen in such a way that the initial temperature of condensation is higher than the initial temperature of boiling. Therefore, it is possible that the initial boiling of the working fluid is achieved by recuperation of heat released in the process of the condensation of the spent working fluid. But in a case where the initial temperature of the heat source used is moderate or low, the range of temperatures of the heat source is narrow, and therefore, the possible range of such recuperative boiling-condensation is significantly reduced and the efficiency of the system described in the prior art diminishes.
U.S. Pat. Nos. 6,769,256, 6,941,757, 6,910,334 and 7,065,969 disclosed modified versions of the systems set forth above.
Thus, there is a need in the art for a new thermodynamic cycle and a system based thereon for enhanced energy utilization and conversion.